Tool wear mechanisms and effects on refill friction stir spot welding of AA2198-T8 sheets

Refill Friction Stir Spot Welding (refill FSSW) is a method for joining similar and dissimilar lightweight metallic materials or thermoplastic polymers. The technique produces welds that feature suitable mechanical properties with advantages such as the possibility of industrial scalability automation. Still, some challenges need to be overcome in order increase adoption this industry. Tool wear key issue friction-based processes, since it impacts process costs quality welds. In study, total 2350 AA2198-T8 sheets were performed effect on probe shoulder was investigated. While did not suffer any considerable after number welds, underwent different areas, distinct mechanisms. Adhesive plastic deformation determined primary damage mechanisms affecting areas shoulder. Mechanical testing selected has shown trend towards reduction lap shear strength (LSS) function tool wear. Macrostructural analysis welds' geometrical features shows profile changes at due led stirred zone area and, consequently, joints’ LSS. Modifications worn suggested possible causes hook height, which identified further determining factor observed all tested surpassed minimum standard requirements aeronautical applications.